Spreading Dynamics of a Precursor Film of Ionic Liquid or Water on a Micropatterned Polyelectrolyte Brush Surface
Spreading Dynamics of a Precursor Film of Ionic Liquid or Water on a Micropatterned Polyelectrolyte Brush Surface
复制标题
DOI：
10.1021/acs.langmuir.0c03260
复制
发表时间：
2021-03-05
期刊：
影响因子：
3.9
通讯作者：
Kobayashi, Motoyasu
中科院分区：
文献类型：
--
作者：
Shiomoto, Shohei;Higuchi, Hayato;Kobayashi, Motoyasu
通过光学显微镜直接观察和选择性染色方法，精确地测量了1-乙基-3-甲基咪唑双(三氟甲基磺酰基)亚胺(EMI-TFSI)或水在微米级线条表面上的微观润湿速度的时间演化。当将液滴放置在染色的线纹刷子表面时，液体穿透并扩散到聚合物刷子层中，形成延伸到宏观接触线之外的前驱体薄膜。伸长分两个阶段进行，先是绝热过程，然后是扩散过程。在绝热过程中，拉伸距离X与水的t(2.6)和EMI-TFSI的t(0.81)成正比。在扩散过程中，前驱膜的推进速度明显降低，水为Xαt(0.66)，EMI-TFSI为X-αt(0.21)，表明扩散过程受润湿体系能量耗散的影响。EMI-TFSI的高粘度和与聚合物刷的强分子相互作用使润湿过程中的熵变很大，导致传播速度变慢。
Time evolution of the microscopic wetting velocity of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI-TFSI) or water on a micrometer-scale line-patterned surface with a poly(3-sulfopropyl methacrylate) brush and a hydrophobic perfluoroalkyl monolayer was precisely measured by direct observation using optical microscopy and a selective dyeing method over a long period (178 days). When a liquid droplet was placed on the dyed linepatterned brush surface, the liquid penetrated and spread into the polymer brush layer, forming a precursor thin film that extended beyond the macroscopic contact line. The elongation proceeded in two stages by an adiabatic process followed by a diffusive process. The elongation distance X increased with time in proportion to t(2.6) for water and t(0.81 )for EMI-TFSI during the adiabatic process. In a diffusive process, the advancing velocity of the precursor film was markedly reduced to be expressed as X alpha t(0.66 )for water and X- alpha t( )(0.21)for EMI-TFSI, indicating that the diffusive process was affected by the energy dissipation of the wetting system. The high viscosity and the strong molecular interaction of EMI-TFSI with the polymer brush gave a large entropy change during the wetting process to result in a slower spreading velocity.